As a conventional linear drive ultrasonic motor, a vibration apparatus described in Patent Literature 1 can be cited as an example (FIG. 22A and FIG. 22B). Here, FIG. 22A and FIG. 22B are diagrams showing a structure of a conventional linear drive ultrasonic motor, where, FIG. 22A is an exploded perspective view and FIG. 22B is a vertical cross-sectional view.
The vibration apparatus shown in FIG. 22A and FIG. 22B includes a case 906 which accommodates a vibrating body 901, a mobile object 904 which passes through the case 906 and makes a contact with the vibrating body 901, and a pressing spring 905 which generates thrust (bias) which brings the mobile object 904 and the vibrating body 901 in a pressurized contact. The pressing spring 905 is installed at an outer side of the case 906. An opening portion is formed in a side of the case 906, facing the vibrating body 901, and the thrust of the pressing spring 905 acts on the vibrating body 901 through the opening portion. In other words, this vibration apparatus has a structure in which, the pressing spring 905 is installed on the outer side of the case 906 while covering the opening portion of the case 906, and a deformed portion (a flat surface portion covering the opening portion) of the pressing spring 905 which generates the thrust, is exposed.    Patent Literature 1: Japanese Patent No. 3524248 Specification